就连最先进的疫苗也只是在小范围的临床实验中进行检验，可能还要经过几年的时间才能证明那种疫苗是否真的有用。
The most advanced of the vaccines have been tested only in small clinical trials. It is likely to take several more years to show if the vaccines really work.
其他专家迅速注意到该实验的前驱性，并意识到该药物还必须经历长时间的实验检验以确定它的安全性和有效性。
Other experts are quick to caution that the tests are preliminary, and that the drug must be tested over much longer periods of time to be sure it is safe and effective.
实验组和对比组时间的平均数差异经过t检验，在0.05的水平上具有显著性。
The mean difference of the post-test was significant at the 0.05 level.
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